Support is requested for the continuation of a comprehensive research program on learning and its facilitation in children with mental retardation or learning handicaps. The fundamental objective of this research program is to improve our understanding of normal and retarded development, particularly those factors related to learning problems and delayed cognitive development. With respect to this goal, it should be noted that two sections are subsumed under the theme: Social and Communicative Processes and Perceptual and Attentional Processes. The basic assumption underlying this program of research is that a problem as complex as mental retardation should be approached by a coordinated research effort, involving several different lines of investigation, but focusing on particular problems related to learning and its facilitation. The problems selected for study vary along a number of dimensions including (a) mild to moderate functional impairments, (b) basic to applied considerations, (c) relatively simple to complex behaviors. Certain important presuppositions are shared by the six projects proposed in this application. These follow from a commitment of the investigators to explore the implications of a "situated cognition" framework and include (a) a focus on behaviors and skills assumed to be at least potentially modifiable, (b) a focus on alternative pathways to learning as appropriate adaptations to biologically or environmentally induced handicaps, (c) a focus on the importance of cue (i.e., stimulus) utilization in learning. Three of the projects focus on some component of social or communication development. These include projects on the facilitation of prelinguistic development, the facilitation of early language development through parent- based intervention, the development of social referencing, nd social influences on early mother/infant dyadic interaction. Three projects investigate perceptual or relational learning processes. These include studies of an instructional approach that utilizes videodisc technology on young at-risk students' acquisition of comprehension and decision-making skills, studies of the effects of varying visual presentation formats in discrimination learning, and studies on the abilities of mildly retarded individuals to perceive certain classes of stimuli with distinctive attributes.